Mapping stimulus-induced nervous activity in small brains by [3H]2-deoxy-D-glucose.

Nervous activity may be localized in anatomical sections of brain tissue by the autoradiographic deoxyglucose technique. The method provides sufficient structural preservation and spatial resolution for detailed functional investigation of complex but small-sized nervous systems when the original technique is modified as follows: (i) use of 3H instead of 14C as radioactive label, (ii) application of labeled deoxyglucose in concentrations close to physiological glucose levels rather than in trace amounts, (iii) stimulation for 4--9 h after deoxyglucose application instead of 20--45 min, (iv) subsequent preparation avoiding aqueous phases at all stages from fixation to autoradiography, and (v) plastic embedding of the tissue such that serial semithin sections of good structural preservation may be routinely cut. Brief aqueous fixation and dehydration at room temperature as has been described for vertebrates apparently cannot preserve stimulus-induced distribution of radioactive label in the brain of the fly Drosophila melanogaster. Aspects of the results that illustrate the potential and some limitations of the present technique are discussed.